# The Most Common Mistake with Moles!

here's a question that can be a little bit tricky and it's a good test of how well you understand

### moles

okay here's a question how many molecules of h2o are in one mole of h2o molecules okay think about this for a sec you can do some math pause the video and when you have your answer turn it back on okay got it so when I asked this question to people I usually get one of these two very#### common

responses okay the first is I don't know and the second is one one molecule of h2o in one mole of h2o molecules unfortunately neither of these is really what I'm looking for the correct answer to this question how many molecules of h2o are in one mole of h2o molecules is 602 hexillion molecules of h2o and this is often abbreviated this number 602 hexillion is often abbreviated as 6.02 times 10 to the 23rd it's just this number written in scientific notation okay so if you got this right awesome great job if this was a little bit tricky for you keep watching and we'll do a quick talk about### moles

so this kind of problem won't confuse you again and you'll be all set with these concepts so what's a mole well I always like to say that a mole is kind of like a dozen except a dozen has 12 things in it and a mole has 602 hexillion things in it that's pretty big it's a lot bigger than a dozen now this number 602 hexillion is really big it's got all these zeros that are a big pain to write so a lot of the times when we want to write this number...we abbreviate it in scientific notation as 6.02 times 10 to the 23rd okay now a lot of people me included get really scared by this number you see this it's like well what do I even do with this I have this 10 to the 23rd and 6.02 but it's really important to keep in mind that this number just a shorthand abbreviation version of 602 hexillion so whenever you see or hear 6.02 times 10 to the 23rd don't freak out just think of it as an abbreviation of 602 hexillion so what's the mole a mole is like a dozen except a dozen has 12 things in it and a mole has 602 hexillion things in and these 602 hexillion things are often abbreviated as 6.02 times 10 to the 23rd so now we can apply what we've learned here to the problem that we first started at the beginning of the video ok so now we know what a mole is and whenever we see it's something talking about a mole we know how many things are in that mole okay so if someone asks how many jellybeans are in one mole of jellybeans and check out these jellybeans here the answer is 602 hexillion jellybeans or we can abbreviate that as 6.02 times 10 to the 23rd jellybeans because there's always 602 hexillion things in a mole of anything or we could have a mole of pennies how many things in a mole of pennies 602 hexillion pennies in that mole or we can abbreviate it as 6.02 times 10 to the 23rd pennies see where this is going now here's a question that we had at the beginning of the video how many molecules of...

h2o are in one mole of h2o molecules well a mole is just another word for 602 hexillion things so there are 602 hexillion h2o molecules in 1 mole of h2o molecules or if we want to abbreviate it there are 6.02 times 10 to the 23rd h2o molecules in one mole